Telephone system.



H. G. WEBSTER.

TELEPHONE SYSTEM.

APPLICATION FILED r1113. 19, 1906.

Patented Dec. 22, 1908.

/wvv/n w ERR M55751? Jim #7 UNTTED STATES PATENT OT FTOE.

HARRY G. WEBSTER, OF CHICAGO, ILLINOIS, ASSIGNOB TO MILO G. KELLOGG, OF CHICAGO, ILLINOIS.

TELEPHONE SYSTEM.

Specification of Letters Patent.

Patented Dec. 22, 1908.

Application filed February 19, 1906. Serial No. 301,900.

To all whom it may concern:

Be it known that I, HARRY G. WEBSTER, a citizen of the United States, and resident of Chicago, county of Cook, and State of Illinois, have invented new and useful Improvements in Telephone Systems, of which the 1 following is a specification.

The present invention relates to telephone systems generally and more particularly to manual systems of a central energy type and comprises certain features of invention, some of which are capable of use in other systems.

One feature of the invention consists in a novel organization in which a four relay linkcircuit is employed with a line circuit having a resistance, such as that of the usual cut-0E and line relays, in bridge of the line limbs.

Another feature of the invention consists in an arrangement of circuits and apparatus by which both a high resistance line relay and a high resistance heat coil, or similar protective device, may be employed. It has been the practice heretofore in the use of such devices to employ a heat coil of relatively'few turns and of low resistance, included directly in the talking circuit. Under these circumstances, it was necessary to use a line relay of relatively low resistance, since, otherwise, in the case of sneak currents coming in over the line, the insulation of the line relay might become charred before the heat coil had been sufiiciently heated to operate. By including the heat coil directly in the talking circuit, it is necessary to keep it of low resistance in order not to interfere with conversation.

A third feature of the invention consists in novel means for applying simultaneously ringing and battery currents to the line so as to maintain the cut-off relay actuated, in that type of system in which a resistance is included in bridge of the telephone line limbs.

The above and other features and objects of the invention will be more fully understood upon reference to the following description taken in connection with the accompanying drawing, in which a system embodying the features of the invention is diagrammatically illustrated, and the scope of the invention will be indicated in the appended claims.

Referring to said drawing, A and B designate two substations which are connected to a central o'lfice C by suitable telephone lines. The equipment at substation A, which may be of any preferred type, is here shown as comprising a call-bell 1 in series with a condenser 2, normally included in bridge of the telephone line limbs 34 by the engagement of the switch-hook 5 with the fixed contact 6. A second normally open bridge, including the transmitter 7 and receiver 8, is closed at the contact 9 by the switch-hook 5 whenever the receiver is removed therefrom. At the central office, the line limbs are extended from the distributing board, indicated by the jumpers 10, to a source of current such as battery 11 and the usual contacts 12 and 13 of the jacks 14.

The extension of the line limb 4 is normally connected to the conductor 15, which is permanently connected with the live pole of the battery 11, by way of the winding of the line relay 16, the contacts 17-18 of the cut-off relay 19, and the winding of the heat coil 20, while the extension of the line limb 3 is normally connected to ground by way of the cut-off relay contacts 2122. The line lamp 23 is connected between the conductor 15 and ground by way of the normally separated line relay contacts 24-25 and the normally closed cut-off relay contacts 2126. The armature contact 17 of the cut-off relay 19 is adapted to engage a front contact 27 to connect the winding of the line relay 16 in bridge of the telephone l ne limb extensions. The armature c0ntact 17 is mechanically connected to a similar contact 28 which is adapted to engage a fixed contact 29 when the cut-0H relay 19 is energized, to connect the contacts 13 of the jacks directly to the line limb 4. The heat coil, which may be of any preferred construc tion, is here shown as comprising a movable core 30 which controls the normally engaging contacts 3132 by which the line limb 4 is completed. These contacts are so constructed that their normal tendency is to separate, thus interrupting the line limb 4, but they are restrained from such movement by soldering the core 30 in the position illustrated with some low fusing solder. As shown, the winding of the heat coil 20 is normally in series with the line limb 4 and, in operation, a sneak current, flowing through the coil for some time, would heat I pressed. The tip contact of the calling plug it suiiiciently to tree its core 20 and allow contacts 31-32 to separate, thus interrupting the line limb 4 until the trouble could be removed.

The equipment and the connections thus far described with reference to substation A are practically duplicated in connection with the substation i5 and the corresponding parts are indicated, in connection with the latter station, with similar primed characters.

At the central ornce, the means for connecting the subscribers lines for conversation comprises an answering plug 33, whose tip contact is connected by strands 3435 to the tip contact of the calling plug 36 and whose sleeve contact is connected by strands 37-38 to the sleeve contact of the calling plug. The strands 34 and 35 on the one hand, and 37 and 38 on the other, are separated by the usual condensers 394O respectively, to permit the transmission of voice currents over the strands and to prevent the flow of battery current. A supervisory lamp 41, associated with the answering end of the link-circuit, has its circuit between the live pole of the battery 11 and ground controlled by the normally open contacts of the relay 42 and the normally closed contacts of the relay 43. The "former relay has its winding connected between the live pole of the battery and the strand 37, while the latter relay has its winding connected between the strand 34 and ground. A supervisory lamp 41, associated with the calling end of the link-circuit, is similarly controlled by the contacts of the relays 42 and 43 which, in turn, are similarly connected, on the one hand, between the live pole of the battery 11 and the strand 38, and on the other, between the strand 35 and ground. The strands 35 and 38 are provided with the usual listening hey levers 4445 which may be depressed to close a bridge between the strands including the condenser 46, the secondary winding of an induction coil 47 and the operators receiver 48. The operators transmitter 49 is included in a local circuit including the battery 50 and the primary winding of the induction coil 47. The strands 35 and 38 are also provided with the ringing key levers 50 51 which normally engage the fixed contacts 52-53 to maintain the continuity of the strands, but which may be depressed to connect the calling generator 54 and the resistance lamp 55 in bridge of the strands. In order to provide a path for current between the live pole of the attery 11 and the sleeve contact of the calling plug 36 at the time the ringing lrey is depressed, the said hey is provided with an additional lever 56 which is directly connected through an impedance 57 to the conductor 15, and is adapted to be engaged by the lever 51 when the listening key is de 36 at this time is directly connected to ground at the point 58.

In the operation of the system, 'a party atsubstation A, desiring to converse with a party at substation B, removes his receiver 8 from its switch-hook 5, thereby completing the normally open bridge between the telephone line limbs 3-4 and com leting a circuit through the winding of the ine relay 16, which may be traced as follows: from the live pole of the battery 11, through conductor 15, winding of the heat coil 20, cut-off relay contacts 18-17, the winding of the line relay 16, jumper 10 at the distributing board, heat coil contacts 32-31, line limb 4, the closed bridge at the substation, line limb 3, jumper 10at the distributing board, 'cutofi relay contacts 2221, to ground. The completion of this circuit will energize the line relay 16 sufficiently to close the contacts 2425, thereby completing a bridge for the line lamp 23 and causing it to light, as an indication to the operator that connection is desired. Upon observing this signal, the operator will insert the answering plug 33 into the answering jack of the line 3 1. This act will complete a circuit through the windings of the supervisory relays 4243 and the cut-off relay 19, as follows: from the live pole of the battery 11, through the winding of the relay 42, plug and jack sleeve contacts, winding of the relay 19, jack and plug tip contacts, strand 34 and the winding of the supervisory relay '43. This will instantly cause the cut-oi'i' relay 19 to attract its armature contacts 21, 17 and 28, thereby interrupting the circuit of the line lamp 23, causing its extinguishment, completing the line limb 4 to the jack contacts 13 and including the winding of the line relay 16 in bridge of the extended line limbs 3 and 4 and in par allel with the winding of the cut-off relay 19. At this time, it will be seen that the line limbs and the strands of the link-circuit are conductively united and that there are three paths for current in bridge of the line limbs one through the switch-hook at the substation, and the others through the windings of the cut-oil and line relays, respectively. With the bridge at the substation thus closed, the flow of current through the wind ing of the relay 43 is suflicient to cause the separation of its contacts and thereby pre vent the lighting of the supervisory lamp 41, while the opening of the bridge at the substation will cut down the current flow through the winding of this relay to such an extent that it will not maintain the relays contacts separated. At the same time, the current through the winding of the relay 42 will energize the latter sufliciently to close its contacts and thus complete the circuit of the supervisory lamp 41 to cause its illumination. The difierence in the action of the relays may be brought about by using a large number of turns in the winding of the relay 42, relative to the number of turns in the winding of the relay 43, or by adjusting the movable contact of the latter relay, or by both means. Upon establishing this connection, the operator will depress the listening key levers 4445 to connect her receiver in bridge of the circuit thus established, to learn the wishes of the calling party. Upon learning that connection is desired with the line 3 4, she will touch the tip contact of the calling plug 36 against one of the jack contacts 13 while maintaining the listening key levers depressed, to determine the idle or busy condition of the line.

If the line is busy, the potential of the contacts 13 will be above that of ground by reason of the supply of current over the sleeve strand of the link-circuit connected with the line. gagement of the tip contact of the plug and the test contact of the jack, a current will flow over the strand 35, through the winding of the supervisory relay 43 to ground, thus altering the normal charge on the condenser 46 and causing a click in the operators receiver, as an indication to her of the busy condition of the line. In case the line is found to be idle, she will insert the calling plug 36 into the jack, thereby completing a circuit through the supervisory relays 4248 and the cut-off relay 19 as follows: from the live pole of the battery 11, through the winding of the relay 42, strand 38, plug and jack sleeve contacts, winding of the cut-oil relay 19, jack and plug tip contacts, strand 35 of relay 48, to ground. The closing of this circuit will cause the cut-oft'relay to attract its armature contacts, thereby interrupting the circuit of the line lamp 23 and connecting the ra'indings of the cut oii and line relays in parallel bridge of the line limbs, as previously pointed out in connection with the line 34. At this time, the current flow through the supervisory relays 42 and 43 will be sufficient to close the contacts of the former, but insuflic-ient to separate the contacts of the latter, thereby maintaining the circuit of the supervisory lamp 41 and causing its illumination. The operator will then depress the ringing key levers 505156, thereby connecting the battery 11 and the calling generator 54 in parallel bridge of the link-circuit. A circuit will thus be completed for ringing current over the line limbs 34 and through the call-bell 1 and condenser 2, while battery current will be supplied to the cut-off relay winding as follows: from the live pole of the battery 11,-through conductor 15, impedance 57, ringing key levers 5651, plug and jack sleeve contacts, winding of the cut-oil relay 19, jack and plug tip contacts, ringing key lever 50, to ground at 58. Under these conditions, as

Conse uentlv u on the en-' soon as the party at substation B answers the call, the path in shunt to the windings of the cut-off and line relays will be completed, thereby increasing the flow of current through the supervisory relays 4243 sutficiently to cause the separation of the contacts of the latter to interrupt the circuit of the supervisory lamp 41 to cause its eXtinguishment. V'Vith the parties thus connected, conversation may be held between the two stations A and B; and. as long as the receivers 8 and 8 remain off their switchhooks, the supervisory lamps 4.1 and 41 will remain dark. As soon, however, as either party hangs up his receiver, the correspond ing supervisory lamp will be lighted, and the lighting of both lamps will be an indication to the operator to disconnect.

Obviously, in carrying out my invention, certain alterations and modifications may be made in the matter herein disclosed without departing from the spirit and sec e of the invention; I, therefore, do not wish to be limited to the specific matter illustrated but aim to cover, by the terms of the appended claims, all such alterations and modifications.

l/Vhat I claim as new and desire to secure by Letters Patent of the United States is 1. A telephone system comprising a telephone line extending in two limbs between two stations, a relatively high resistance heat coil and a relatively high resistance electromagnet in circuit therewith, and means "for completing a talking circuit over said line excluding said heat coil and corn necting said magnet in bridge of the line limbs.

2. A telephone system comprising a telephone line extending in two limbs between two stations, a relatively high resistance heat coil and a relatively high resistance electromagnet in circuit therewith, means actuated by the heating of said coil to vary the line connections, a signal controlled by 'said electromagnet, and means for completing a talking circuit over said line excluding said heat coil and connecting said magnet in bridge of the line limbs.

3. A telephone system comprising a telephone line extending in two limbs from a substation to a central office, a link-circuit for making connection to said line, means for holding conversation over said line and link-circuit, a relatively high resistance heat coil and a relatively high resistance electromagnet in circuit with said line, means actuated by the heating of said coil to var the line connections, a signal controlled b r said electromagnet, and means operative upon the connection of said link-circuit to said line to complete a talking circuit excluding said heat coil and connecting said magnet in bridge of the line limbs.

4. A telephone system comprising a tele- &

- relatively high resistance electromagnet in circuit with said line, means actuated by the heating of said coil to vary the line connections, a signal controlled by said electromagnet, means operative upon the connection of said link-circuit tosaid line to connect said electromagnet in bridge of the talking circuit, means under the control of the subscriber for closing a path in shunt to said electromagnet, and a signal associated with the link-circuit displayed and effaced by the opening and closing of said shunt path.

5. A telephone system comprising a telephone line extending from a substation to a central office, a link-circuit for making connection to said line, means for holding conversation over said line and link-circuit, a relatively high resistance heat coil and a relatively high resistance electromagnet in circuit with said line, means actuated by the heating of said coil to vary the line connections, a signal controlled by said electromagnet, means operative upon the connection of said link-circuit to said line to connect said electromagnet in bridge of the talking circuit and to disconnect said heat coil therefrom, means under the control of the subscriber for closing a path in shunt to said electromagnet, and a signal associated with the link-circuit displayed and effaced by the opening and closing of said shunt path.

6. A telephone system comprising a telephone line extending from a substation to a central oflice, a link-circuit for making connection to said line, means for holding conversation over said line and link-circuit, a relatively high resistance heat coil and a relatively high resistance line relay in circuit with said line, means actuated by the heating of said coil to varythe line connections, a line signal normally controlled by said line relay, a relay for destroying said control, means operative upon the connection of said link-circuit to said line to connect said relays in bridge of the talking circuit, means under the control of the subscriber for closing a path in shunt to said relays, and a signal associated with the link-circuit displayed and eflaced by the opening and closing of said shunt path.

7. A telephone system comprising a telephone line extending from a substation to a central office, a link-circuit for making connection to said line, means for holding conversation over said line and link-circuit, a rela tively high resistance heat coil and a relatively high resistance line relay in circuit with said line, means actuated by the heating of said coil to vary the line connections, a line signal normally controlled by said line relay, a relay for destroying said control, means operative upon the connection of said link-circuit to said line to connect said relays in bridge of the talking circuit and to disconnect said heat coil therefrom, means under the control of the subscriber for closing a path in shunt to said relays, and a signal associated with the link-circuit displayed and efiaced by the opening and closing of said shunt path.

8. A telephone system com rising a telephone line extending in two limbs from a substation to a central office, suitable connection terminals therefor, a two strand linkcircuit and a two contact connecting plug for making connection to said line, means for holding conversation over said line and linkcircuit, a resistance associated with said line, a line signal, a controlling relay therefor,

two relays associated with said link-circuit,

means for displaying a signal in response to the actuation of one of said link-circuit relays only and for efiacing said signal in response to the actuation of the other, means operative upon the connection of said link-circuit to said line to actuate the linkcircuit signal displaying relay by completing a circuit over portions of both sides of the talking circuit, the link-circuit relay windings and through said resistance and line relay winding in parallel, and means under the control of the subscriber for actuating said signal efl'acing relay by closing a low resistance path in shunt to said resistance and line relay winding.

9. A telephone system com rising a telephone line extending in two limbs from a substation to a central oliice, suitable connection terminals therefor, a line signal associated therewith, a line relay for normally controlling the display of said signal, a cut-off relay for destroying said control, a two strand link-circuit and a two contact connecting plug for making connection to said line, means for holding conversation over said line and link-circuit, two relays associated with said link-circuit, means for displaying a signal in response to the actuation of one of said relays only and for eifacing said signal in response to the actuation of the other, means operative upon the connection of said link-circuit to said line to actuate the link-circuit signal-displaying relay by com leting a circuit through the link-circuit re ays including the line relay and cut-off relay windings in parallel, and meansunder the control of the subscriber for actuating said link-circuit signal-effacing relay by increasing the current flow in both of said link-circuit relay windings.

10. A telephone system com rising a telephone line extending in two imbs from a substation to a central ofiice, suitable connection terminals therefor, a line signal associated therewith, a line relay for normally controlling the display of said signal, a cut-oil relay for destroying said control, a two strand link-circuit and a two contact connecting plug for making connection to said line, means for holding conversation over said line and link-circuit, two relays associated with said link-circuit, means for displaying a signal in response to the actuation of one of said relays only and for efiacing said signal in response to the actuation of the other, means operative upon the connection of said link-circuit to said line to actuate the link circuit signal displaying relay by completing a circuit through the link-circuit relays including the line relay and cut-off relay windings in parallel, and means under the control of the subscriber for actuating said link-circuit signal-efit'acing relay by closing a path in shunt to the line relay windings.

11. A telephone system com rising a telephone line extending in two imbs from a substation to a central office, suitable connection terminals therefor, a line signal associated therewith, a line relay normally controlling the display of said signal, a cutoil relay for destroying said control, a two strand link-circuit and two contact con' necting plug for making connection to said line, means for holding conversation over said line and link-circuit, a source of current, a supervisory relay having a relatively large number of turns connected between the live pole of said source of current and one side of said link-circuit, a second supervisory re ay having a relatively few number of turns connected between the other pole of said source of current and the other side of said linkcircuit, means for displaying a signal in response to the actuation of the former relay only and for efiacing said signal in response to the actuation of the latter relay, means operative upon the connection of said linkcircuit to said lne to actuate said former supervisory relay by closing a circuit through both supervisory relays including the line relay and cut-01f relay windings in parallel, and means under the control of the subscriber for actuating said latter supervisory relay by closing a path in shunt to the line relay windings.

12. A telephone system comprising a telephone line extending in two limbs from a substation to a central oliice, a two strand link-circuit for making a connection to said line, means for holding conversation over said line and link-circuit, a line relay normally under the control of the subscriber, electromagnetic means for destroying said normal control having an energizing winding in bridge of the talking circuit, means under the control of the operator for connecting energizing windings of said electromagnetic means and said line relay in parallel bridge of the telephone line, supervisory aJparatus and a battery in bridge of the linkcircuit strands, and in series with said energizing windings of said electromagnetic means and said line relay and means under the control of the operator for interrupting said link-circuit bridge and simultaneously connecting in parallel said battery and a source of ringing current in bridge of said strands whereby the battery current will maintain said electromagnetic means actuated and ringing current will be transmitted to the connected substation.

In witness whereof, I hereunto subscribe my name this 15th day of Feby., All, 1906.

HARRY G. WEBSTER. Witnesses:

H. C. OLMSTEAD, G. E. MUELLER. 

